Description:
------------
Perhaps that's a libcurl bug, but the curl extension multi functionality consistently fails with 7.29.0 . For instance this snippet based on ext/curl/tests/curl_multi_init_basic.phpt

$mh = curl_multi_init();
curl_multi_close($mh);

Basically it does crash always if no handles were added between init and cleanup. Ther corresponding snippet in c

#include <curl/curl.h>

int main(void)
{
  CURLM *multi_handle;

  multi_handle = curl_multi_init();

  curl_multi_cleanup(multi_handle);

  return 0;
}

That snippets do successfully work with the libcurl versions prior to 7.29.0 . The issue introduces itself starting with this commit in libcurl included in 7.29.0

https://github.com/bagder/curl/commit/c43127414d89ccb9ef6517081f68986d991bcfb3#L10R1776

And the commit is related to a big change explaned here http://daniel.haxx.se/blog/2013/01/17/internally-were-all-multi-now/

The issue is consistently reproduceable on linux and windows through all PHP versions.

Expected result:
----------------
no crash

Actual result:
--------------
#0  _php_curl_multi_close (rsrc=0xb707259c) at /home/weltling/dws/src/php-5.5-nts/ext/curl/multi.c:349
#1  0x085902ff in list_entry_destructor (ptr=0xb707259c) at /home/weltling/dws/src/php-5.5-nts/Zend/zend_list.c:183
#2  0x0858d72e in zend_hash_del_key_or_index (ht=0x8aa7158, arKey=0x0, nKeyLength=0, h=4, flag=1)
    at /home/weltling/dws/src/php-5.5-nts/Zend/zend_hash.c:531
#3  0x0858ffed in _zend_list_delete (id=4) at /home/weltling/dws/src/php-5.5-nts/Zend/zend_list.c:57
#4  0x081d1d8b in zif_curl_multi_close (ht=1, return_value=0xb7070b3c, return_value_ptr=0x0, this_ptr=0x0, 
    return_value_used=0) at /home/weltling/dws/src/php-5.5-nts/ext/curl/multi.c:330
#5  0x085b7f4b in zend_do_fcall_common_helper_SPEC (execute_data=0xb70540c4)
    at /home/weltling/dws/src/php-5.5-nts/Zend/zend_vm_execute.h:542
#6  0x085bdc7b in ZEND_DO_FCALL_SPEC_CONST_HANDLER (execute_data=0xb70540c4)
    at /home/weltling/dws/src/php-5.5-nts/Zend/zend_vm_execute.h:2293
#7  0x085b695c in execute_ex (execute_data=0xb70540c4) at /home/weltling/dws/src/php-5.5-nts/Zend/zend_vm_execute.h:356
#8  0x085b7023 in zend_execute (op_array=0xb70713a8) at /home/weltling/dws/src/php-5.5-nts/Zend/zend_vm_execute.h:381
#9  0x0857ed2d in zend_execute_scripts (type=8, retval=0x0, file_count=3)
    at /home/weltling/dws/src/php-5.5-nts/Zend/zend.c:1316
#10 0x085023ec in php_execute_script (primary_file=0xbfffdff0) at /home/weltling/dws/src/php-5.5-nts/main/main.c:2479
#11 0x086a7d59 in do_cli (argc=2, argv=0xbffff284) at /home/weltling/dws/src/php-5.5-nts/sapi/cli/php_cli.c:988
#12 0x086a8ec3 in main (argc=2, argv=0xbffff284) at /home/weltling/dws/src/php-5.5-nts/sapi/cli/php_cli.c:1364